Veritas Storage Foundation 5.1 SP1 Advanced Features Administrator"s Guide (5900-1503, April 2011)

Warning: Always unmount the snapshot volume (if this is mounted) before
performing a snapback. In addition, you must unmount the file system
corresponding to the primary volume before using the resyncfromreplica option.
Adding plexes to a snapshot volume
If you want to retain the existing plexes in a snapshot volume after a snapback
operation, you can create additional snapshot plexes that are to be used for the
snapback.
To add plexes to a snapshot volume
1
Use the following vxprint commands to discover the names of the snapshot
volume’s data change object (DCO) and DCO volume:
# DCONAME=`vxprint [-g diskgroup] -F%dco_name snapshot`
# DCOVOL=`vxprint [-g diskgroup] -F%log_vol $DCONAME`
2
Use the vxassist mirror command to create mirrors of the existing snapshot
volume and its DCO volume:
# vxassist -g diskgroup mirror snapshot
# vxassist -g diskgroup mirror $DCOVOL
The new plex in the DCO volume is required for use with the new data plex
in the snapshot.
3
Use the vxprint command to find out the name of the additional snapshot
plex:
# vxprint -g diskgroup
snapshot
4
Use the vxprint command to find out the record ID of the additional DCO
plex:
# vxprint -g diskgroup -F%rid $DCOVOL
5
Use the vxedit command to set the dco_plex_rid field of the new data plex
to the name of the new DCO plex:
# vxedit -g diskgroup set dco_plex_rid=dco_plex_rid
new_plex
The new data plex is now ready to be used to perform a snapback operation.
251Administering volume snapshots
Creating traditional third-mirror break-off snapshots